Catheter for high pressure injections

ABSTRACT

A medical catheter is formed from a hub within which an elongated flexible tube is disposed. The bore of the tubing within the hub is tapered to accept the tapered tip of a male connector. The tubing is coextensive with the shaft of the hub. A method for fabricating the medical catheter involves mounting the hub on a mandrel, which has a tapered portion, adapted to be positioned within the hub, and an elongated pilot extending from the tapered portion through the hub. Heat softenable catheter tubing is fed onto the tapered portion until resistance is met, then the tubing while heat softened, is forced over the tapered portion of the mandrel in the recess between the tapered portion and the hub. The tubing is solidified and the joined catheter removed from the mandrel.

United States Patent Hubert CATHETER FOR HIGH PRESSURE INJECTIONS FranzHans Hubert, Carlstadt, NJ.

Becton, Dickinson and Company, East Rutherford, NJ.

Feb. 1, 1971 Inventor:

Assignee:

Filed:

Appl. No.:

US. Cl. ..128/2.05 R, 128/348 Int. Cl. ..A6lm 25/00 Field of Search..128/2 R, 2 M, 2.05 R, 214.4,

References Cited UNITED STATES PATENTS Jiv- FOREIGN PATENTS ORAPPLICATIONS 463,704 10/1968 Switzerland ..128/348 785,136 10/1957GreatBritain ..128/349R Primary Examiner-Dalton L. TruluckAtt0rney-Kane, Dalsimer, Kane, Sullivan & Kurucz [5 7] ABSTRACT Amedical catheter is formed from a hub within which an elongated flexibletube is disposed. The bore of the tubing within the hub is tapered toaccept the tapered tip of a male connector. The tubing is coextensivewith the shaft of the hub. A method for fabricating the medical catheterinvolves mounting the hub on a mandrel, which has a tapered portion,adapted to be positioned within the hub, and an elongated pilotextending from the tapered portion through the hub. Heat softenablecatheter tubing is fed onto the tapered portion until resistance is met,then the tubing while heat softened, is forced over the tapered portionof the mandrel in the recess between the tapered portion and the hub.The tubing is solidified and the joined catheter removed from themandrel.

8 Claims, 4 Drawing Figures PATENTEnmzolm 3721.231

BY {@JM $4 M 9 5.0

ATTORNEYS CATHETER FOR HIGH PRESSURE INJECTIONS BACKGROUND OF THEINVENTION The present invention is directed to a medical catheterparticularly suitable for high pressure applications. In particular, itis directed to a new method of joining catheter tubing to a surroundinghub to obtain an optimal flow of fluid from a source interengaged withthe hub and tubing, through the catheter tubing.

In the past flexible catheter tubing has been joined at one end to theneck of a connecting hub by the use of adhesives, heat-scalable tubing,fillets, ribbed adapters and the like. While for certain purposes, suchconventional joint is satisfactory, nonetheless, for certain highpressure applications and specialized techniques, such joint is subjectto several defects. Since the surface area of the bonding surfacesbetween the catheter tubing and hub is small compared to the totalsurface area of the hub, the joint tends to weaken under high pressureor turbulent flow. This weakening can result in axial movement of thetubing with respect to the hub, thereby further disrupting flow and/orrupture of the bond between the catheter and hub. This is effect isparticularly pronounced during dye injection employing high pressureangiocardiography injection machines where an internal pressure in theorder of 1,100 lbs. per square inch is developed within the hub andcatheter.

For the above and other applications it is particularly desirable thatthe hub and catheter be adapted to receive dye or other fluids from amale connector capable of interengaging the hub and catheter. A highlysatisfactory male connector for this purpose is the male LUER-LOKconnector. Such a connector is characterized by an internally threadedsleeve portion adapted to interlock with a hub and a centrallyprojecting tapered tip adapted to form a frictional fit with a taperedcentral bore of a female hub.

The prior art has taught various methods for joining tubing, such asgarden hoses, to coupling members. An example of such a method isdisclosed in US. Pat. No. 2,686,337. Such methods are not readilyadapted to medical catheters employed in combination with maleconnectors with tapered tips. To ensure a smooth transition between thefluid issuing from the male tapered tip and catheter tubing, it has nowbeen found necessary to form catheter tubing with a tapered internalbore and joing the tubing coextensive with the inner shaft of a femalehub. The prior art, including the above noted patent, has not provided atechnique for achieving a solution to this problem.

SUMMARY OF THE INVENTION It is a primary object of this invention toprovide a method for joining flexible tubing with a rigid hub such thata pressure-resistant joint is formed.

It is another object of the invention to provide a preformed catheteruseful for high pressure applications and adapted to mate with a maleconnector having a tapered tip to provided a smooth transition betweenfluid issuing from the tapered tip and the catheter tubing.

The above and other objects are met in a method for joining a flexibletubular catheter coextensively with the inner shaft of a female rigidhub, the catheter and hub being adapted to interlockingly engage thetapered tip and sleeve of a male connector. The hub is mounted on amandrel having a tubular housing with a protruding tapered portionterminating in an elongated pilot, the pilot adapted to protrude throughthe hub. When the hub is mounted properly on the tapered portion, thereis a tapered recess between the outer surface of the tapered portion andthe inner shaft of the hub. Flexible, heat softenable catheter tubing isfed over the pilot and onto the tapered portion of the mandrel untilresistance is met. While heat softened, the catheter tubing is forcedover the tapered portion of the mandrel to completely fill the recessbetween the tapered. portion and the hub. The tubing is solidified andthe joined catheter and hub are removed from the mandrel.

The medical catheter formed by the above method is particularly adaptedfor high pressure applications, since the flexible tubing is coaxiallymounted within the hub coextensive with the entire shaft of the hub. Thethickness of the tubing within the hub gradually increases as oneprogresses from the mouth to the central portion of the tubing withinthe hub, thereby forming an internally tapered portion. This taperedportion of the tubing is particularly adapted to receive the tapered tipof a male connector. A slip-resistant smooth fit is thereby achieved.

BRIEF DESCRIPTION OF DRAWING The invention will be more fully understoodfrom the following detailed description of an illustrative embodimentshown by the accompanying drawing, in which:

FIG. 1 is a schematic view showing the apparatus of the inventionpartially emplanted in a patient in a roentgenography application;

FIG. 2 is an exploded fragmentary enlargement illustrating the method offorming the medical catheter on a mandrel;

FIG. 3 is a fragmentary sectional enlargement illustrating the relativepositions of the mandrel and hub after formation of a medical catheter;and

FIG. 4 is an enlarged, fragmentary view, partially in sectionillustrating the medical catheter of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS FIGS. 2 and 3 illustrate the methodfor forming the catheter of the invention. A mandrel 10 is provided forengaging the hub 12 of the medical catheter. The mandrel includes a baseportion 14, a tapered cylindrical anvil l6 and an elongated pilot 18.

The diameter of pilot I8 is slightly less than the internal diameter offlexible tubing 24, and offers substantially no resistance when tube 24is slid over the pilot. The maximum diameter of tapered anvil 16 is lessthan the internal diameter of the shaft of hub 12 so as to provide atapered recess when hub 12 is mounted thereover.

To form the medical catheter of the invention, hub 12 is placed overpilot l8 and anvil 16. Flexible, heat softenable catheter tubing 24 isnext fed over pilot 18 and onto tapered anvil 16 until resistance ismet.

In the preferred process where large quantities of assemblies are to bemade, an internally heated mandrel is employed to melt tubing 24 andcompletely fill the recess between the anvil and the internal shaft ofthe hub. The heating cycle is started and the tubing is heated to itssoftening temperature. Pressure is applied to the tubing in thedirection of base 14 and the softened tubing flows into the recessbetween the anvil and hub, filling the entire space. The heating cycleis terminated, and the joint quickly cools so that the catheter tubingis firmly emplanted within the hub.

In order to provide a firmer joint between the tubing 24 and hub 12,recess 26 is provided in the form of an annular channel about the innerperiphery of the shaft of the hub. During formation of the medicalcatheter, the heat softened tubing material flows into hub recess 26.Upon solidification therein, the tubing resists axial movement withinthe shaft of the hub. If desired, additional recesses 28 may be providedin the hub for this purpose.

Turning now to FIG. 4, a medical catheter of the invention isillustrated. The catheter comprises a hub 12 having a partially taperedshaft therethrough and a flexible catheter 24 joined to the shaft of thehub and coextensive with the shaft. The hub is formed from a rigidmaterial, such as a thermoplastic or thermosetting resin. A preferredmaterial is polypropylene. The hub may be vacuum formed employing asuitable shaped die. The hub is generally cylindrical in shape.

The hub has an externally threaded cylindrical shell portion 22 adaptedto interengage the surrounding sleeve of a male connector, particularlya male LUER- LOK connector having a centrally protruding tapered hollowtip (not shown). A tapered portion 32 of the hub extends from thecylindrical shell portion 22 to an integral neck portion 34 of the hub.In order to facilitate gripping thehub a pair of opposed protrudingwings 36, 36' are integrally associated with the hub and extend from theterminal end of the neck portion of the hub to the joining point betweenthe threaded outer shell and the tapered portion of the hub.

The internal diameter of the hub shaft concentrically spaced within hubshell 22 and extending therethrough is greater than the tapered tip ofthe male luer connector employed in combination with the hub forroentgenography purposes or the like. The hub shaft in the neck portionis of slightly greater diameter than the outer diameter of the flexiblecatheter tubing inserted therein such that a slip fit is formed. Theshaft of the hub is tapered between the neck portion and the shellportion.

The catheter tubing associated with the hub has a first portioncoextensive with the shaft of the hub. From the mouth of the threadedshell portion of the hub, the tubing is of progressively greaterthickness such that a luer slip is formed which is adapted to receivethe male tapered tip of a LUER-LOK connector. The thickness of thecatheter tubing is greatest within the tapered portion of the hub.

At least one recessed annular channel is provided within the shaft ofthe hub, the tubing completely filling the recessed portions. By thisinnovation the tubing is safeguarded against undesirable axial movementwithin the shaft ofthe hub.

The elongated hollow catheter tubing 24 terminates at one end at themouth 38 of the hub, and at the other end in blunt taper 40. Asillustrated in FIG. 4, adjacent the blunt end of the tubing there arespaced a series of outlet ports 42 for receiving or discharging liquids.The arrangement and size of the outlet ports is determined,

in part, upon the specific environment in which the catheter isemployed. The various possible arrangements of ports are well known tothe art.

The flexible, hollow catheter tubing is formed, preferably, fromheat-softenable materials, such as thermoplastic and thermosettingresins. A particularly preferred material is pressure resistantpolyethylene tubing.

Turning now to FIG. 1, it is seen that the medical catheter of theinvention may be employed for roentgenography applications among others.For this purpose it is desirable that the tubing be formed fromradiopaque materials, such as a leaded polyethylene. Such tubing isgenerally from about 0.04 0.05 inch in thickness.

In use, the blunt tapered end 40 of the catheter is introduced into asuitable vessel in the body by conventional techniques. The maleconnecting end 52 of a suitable adapter 44 is securely engaged to themedical catheter 48. A particularly preferred adapter is the well-knownflexible LUER-LOK connecting set available from Becton, Dickinson andCo. A conventional die injection device 46 is employed to inject dieinto the adapter, through the medical catheter 48, and into the body 50.

The invention is not to be limited except as set forth in the followingclaims:

lclaim'.

l. A catheter for high pressure applications adapted for connection to asource of fluid comprising:

a rigid hub of a first plastic material having a passagewaytherethrough;

said hub having means on the exterior surface thereof to facilitate itsconnection to a fluid source;

an elongated flexible tube ofa second plastic material with a passagewaytherethrough having an end adapted for insertion into the body and saidtube including means therein to facilitate connection to a fluid source;and said flexible tube having the other end thereof extendingsubstantially through said hub passageway and being connected to the hubon a substantial portion of the inner surface of the hub by beingdeformable under pressure and heat below the deformation temperature ofthe first plastic material to permit the positioning of one end portionthereof into a substantially coaxial concentric location in the hub withthe outer wall of said one end portion in rigid interengagement with theadjacent inner wall of the hub thereby preventing axial movement of saidone end portion with respect to said hub during use ofthe catheter.

2. The invention in accordance with claim 1 wherein the first plasticmaterial is polypropylene and the second plastic material ispolyethylene.

3. The invention in accordance with claim 1 wherein the means on theexterior surface of the hub to facilitate its connection to a fluidsource includes a threaded end portion for interengagement with athreaded corresponding surface on the fluid source, and the means in thetube to facilitate connection to the fluid source includes a taperedinner surface for frictional interengagement with corresponding surfaceson the fluid source.

4. The invention in accordance with claim 3 wherein the hub has atapered portion extended axially from said threaded outer surfaceportion and a cylindrical neck portion extending axially from thetapered portion.

5. The invention in accordance with claim 1 wherein the end of said tubedistal from said hub terminates in a blunt tapered tip adapted to beintroduced into a body vessel, and a plurality of ports communicatingwith the passageway through the tube and being spaced adjacent said tipof the tube.

6. The invention in accordance with claim 1 wherein the hub has at leastone annular channel recess on the

1. A catheter for high pressure applications adapted for connection to asource of fluid comprising: a rigid hub of a first plastic materialhaving a passageway therethrough; said hub having means on the exteriorsurface thereof to facilitate its connection to a fluid source; anelongated flexible tube of a second plastic material with a passagewaytherethrough having an end adapted for insertion into the body and saidtube including means therein to facilitate connection to a fluid source;and said flexible tube having the other end thereof extendingsubstantially through said hub passageway and being connected to the hubon a substantial portion of the inner surface of the hub by beingdeformable under pressure and heat below the deformation temperature ofthe first plastic material to permit the positioning of one end portionthereof into a substantially coaxial concentric location in the hub withthe outer wall of said one end portion in rigid interengagement with theadjacent inner wall of the hub thereby preventing axial movement of saidone end portion with respect to said hub during use of the catheter. 2.The invention in accordance with claim 1 wherein the first plasticmaterial is polypropylene and the second plastic material ispolyethylene.
 3. The invention in accordance with claim 1 wherein themeans on the exterior surface of the hub to facilitate its connection toa fluid source includes a threaded end portion for interengagement witha threaded corresponding surface on the fluid source, and the means inthe tube to facilitate connection to the fluid source includes a taperedinner surface for frictional interengagement with corresponding surfaceson the fluid source.
 4. The invention in accordance with claim 3 whereinthe hub has a tapered portion extended axially from said threaded outersurface portion and a cylindrical neck portion extending axially fromthe tapered portion.
 5. The invention in accordance with claim 1 whereinthe end of said tube distal from said hub terminates in a blunt taperedtip adapted to be introduced into a body vessel, and a plurality ofports communicating with the passageway through the tube and beingspaced adjacent said tip of the tube.
 6. The invention in accordancewith claim 1 wherein the hub has at least one annular channel recess onthe inner surface of the hub and positioned so that the tube whendeformed under pressure and heat enters said channel and solidifiestherein.
 7. The invention in accordance with claim 1 wherein a pair ofopposed wings extend outwardly from said hub to form a gripping surfacefor manipulating the catheter.
 8. The invention in accordance with claim1 wherein the one end portion of said tube positioned within said hubhas a central portion of greater thickness than the two distal end partsof the one end portion of the tube.